Antioxidants from steamed used tea [Camellia sinensis] leaves and their reaction behavior

The most efficient steaming conditions below 200degC for extracting antioxidants from used tea leaves and their reaction behavior during the steaming treatment were investigated. The antioxidative activity of the steamed extracts increased with increasing steaming temperature, and the yield of the e...

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Bibliographic Details
Published in:Bioscience, biotechnology, and biochemistry biotechnology, and biochemistry, 2008-07, Vol.72 (7), p.1682-1689
Main Authors: Nomizu, K(Tokyo Univ. (Japan)), Kashida, K, Makino, R, Ohara, S
Format: Article
Language:English
Subjects:
antioxidant
ANTIOXIDANTES
ANTIOXIDANTS
Antioxidants - analysis
Antioxidants - isolation & purification
ANTIOXYDANT
BEBIDAS
BEVERAGES
Biological and medical sciences
BOISSON
CAFEINA
CAFEINE
CAFFEINE
CAMELIA SINENSIS
CAMELLIA SINENSIS
CATECHIN
Catechin - analogs & derivatives
Catechin - analysis
Catechin - isolation & purification
CATECHINE
CATEQUINA
epimerization
ESPECTROSCOPIA RMN
FEUILLE
FREE RADICALS
Fundamental and applied biological sciences. Psychology
HOJAS
LEAVES
NMR SPECTROSCOPY
Plant Leaves - chemistry
RADICAL LIBRE
RADICALES LIBRES
SPECTROSCOPIE RMN
Steam
steaming
Tea - chemistry
Temperature
used tea leaves
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Summary:The most efficient steaming conditions below 200degC for extracting antioxidants from used tea leaves and their reaction behavior during the steaming treatment were investigated. The antioxidative activity of the steamed extracts increased with increasing steaming temperature, and the yield of the ethyl acetate extract fraction from each steamed extract showing the greatest antioxidative activity also increased. Caffeine, (-)-catechin, (-)-epicatechin, (-)-gallocatechin, (-)-epigallocatechin, (-)-catechin gallate, (-)-epicatechin gallate, (-)-gallocatechin gallate, (-)-epigallocatechin gallate and gallic acid were identified from the ethyl acetate extract fraction. Quantitative analyses demonstrated that the catechins with a 2,3-cis configuration decreased with increasing steaming temperature, whereas the corresponding epimers at the C-2 position increased. Each pair of epimers showed similar antioxidative activity to each other, indicating that the epimerization reaction did not contribute to the improved antioxidative activity. It is concluded from these results that the improvement in antioxidative activity at higher steaming temperatures was due to the increased yield of catechins and other antioxidants.
ISSN:0916-8451
1347-6947
DOI:10.1271/bbb.70762